Wireless devices, such as wireless telephones and personal digital assistants, are increasingly used to connect to a network such as the Internet. A wireless device connects to the Internet by establishing a communication link with a base unit that is connected to the Internet. The wireless device will establish a link with a base unit according to some wireless communication protocol, such as Code-Division Multiple Access (CDMA), the “Bluetooth” wireless standard, or one of the 802.11 specifications of the Institute of Electrical and Electronics Engineers (IEEE). Once the wireless link is established with the base unit, the wireless device can communicate over the Internet, such as by sending and receiving packets according to a Transfer Control Protocol/Internet Protocol (TCP/IP) connection.
In order to maintain an established network connection (e.g., TCP/IP connection for the Internet), the wireless device is required to maintain continuous communication with a base unit according to the wireless protocol that was originally used to establish the connection. If the wireless device is moved to a coverage zone of a base unit that operates in accordance with a different protocol, then the network connection is usually broken and a new connection using the different protocol is established. To re-establish a connection within the new coverage zone, the wireless device may need to be re-initialized and re-authenticated according to the different protocol used in the new coverage zone. This handoff process where the existing connection is terminated before the new connection can be re-established is sometimes referred to as a “hard handoff”.
For example, FIG. 1 illustrates a “hard handoff” process in a wireless communication system 100 having three wireless communication protocols, CDMA, Bluetooth, and 802.11, within four different coverage zones, Zone A, Zone B, Zone C, and Zone D. Each zone is identified with a respective circle to denote primary area of geographic coverage, with Zone D being the largest circle, encompassing the area representing a CDMA coverage zone for a base station. When a wireless device 102 operating within Zone A with the 802.11 protocol is desired to move to Zone B with the same 802.11 protocol, the wireless device 102 must travel between Zone A and Zone B through Zone D operating with the CDMA protocol. In this case, the network connection made through the 802.11 protocol 104 while in Zone A needs to be terminated, approximately at a location 106, and a new network connection established substantially at the same time, at 108, through the CDMA protocol for wireless communication while the device 102 transits in Zone D. Once the wireless device 102 enters Zone B, the CDMA connection can be terminated at 110 and another new network connection can be established in Zone B, at 112, through the 802.11 protocol. A similar process may be required for the wireless device 102 when it is moving from Zone A (with the 802.11 protocol) to Zone C (with the Bluetooth protocol).
The above-mentioned “hard handoff” process is illustrated in a block diagram 200 in FIG. 2. The wireless device 102 connects to a host 202 through one of several base units 204A, 204B, 204C, 204D that are connected to the Internet. A service provider 206A, 206B, 206C, or 206D corresponding to the respective selected base unit 204A, 204B, 204C, 204D connects the base unit to the Internet. Although four base unit/service provider pairs are illustrated in FIG. 2, it should be understood that a greater or lesser number of base units and service providers might be available to a particular wireless device. Moreover, two or more base units might connect to the Internet through the same provider.
Thus, if the wireless device 102 is currently connected to the host 202 through an 802.11 base unit 204A through a service provider 206A, and it is necessary or desired to connect to the host 202 through another protocol, for example the CDMA base unit 204C, the wireless device 102 will need to terminate its connection to the 802.11 base unit 204A, and initialize and establish a new connection to a CDMA base station 204C and the service provider 206C before the new connection can be made. This adds delay to inter-protocol communications and makes such roaming more complicated. Accordingly, for a wireless device that connects to a host through a network while roaming between coverage zones of various protocols, a protocol transfer process through multiple terminations and re-establishments of a network connection is cumbersome and undesirable.
In view of the foregoing discussion, there is a need for a network connection configuration that allows the wireless device to more efficiently roam between various communication protocols without the repeated terminations and re-establishments of the network connection. The present invention solves this need.